The present invention relates to aluminum-base alloys which may be employed for manufacturing air-conditioning units, components of thermal equipment and other items exposed to high temperatures in their operating environment.
The alloy of this invention combines excellent high-temperature resistance and tightness with good processability.
It can be most advantageously employed for manufacturing intricately shaped structural components, such as heat-exchanger housings exposed to elevated internal pressures of liquid or gaseous media and to high temperatures, on the order of 400.degree. C.
It is known in the art to employ aluminum-base alloys (German Pat. No. 479,528) one of which comprises, wt.%: from 3 to 12 cerium and from 2 to 20 copper, while another from 2 to 12 cerium and from 1 to 8 silicon, as well as solid solution-forming constituents such as magnesium and zinc or high-melting elements such as titanium, molybdenum and tungsten.
The foregoing patent claims that said alloys display improved mechanical properties.
However, aluminum-base alloys containing copper, cerium and silicon in the specified amounts cannot have adequately high processing and mechanical properties.
Thus, the 20-wt.% copper and 12-wt.% cerium levels reduce the plasticity of the alloy and detract from its corrosion resistance.
There also exists an aluminum-base alloy ("Metal Progress" Journal, vol. 61, No. 6, pp. 162-6, 1952, U.S.A.) which has an unstable chemical composition (since the misch metal is a waste product of uranium production).
For this reason, the latter known alloy shows inadequate mechanical properties (ultimate strength, from 9.0 to 13.0 O kg/sq.mm.; percentage elongation, from 0.5 to 1.5).
It is likewise known in the art to employ an aluminum-base alloy comprising, wt.%: misch metal, from 8.5 to 10.0; copper, from 1.5 to 2.0; silicon, from 1.2 to 2.2; manganese, from 0.7 to 0.9; chromium, from 0.1 to 0.3; titanium, from 0.1 to 0.2; zirconium, from 0.1 to 0.3; and iron, from 1.0 to 2.0. The latter alloy is also found wanting as far as its mechanical properties are concerned (ultimate strength, from 12.0 to 14.0 kg/sq.mm.; percentage elongation, from 0.8 to 2.0)
The foregoing alloys have not found industrial application for manufacturing mold castings designed to operate at high temperatures and pressures because their mechanical properties fall short of meeting modern requirements.
Currently, there is a need for aluminum-base alloys with improved processing properties for manufacturing air-conditioning units, components of thermal equipment and other products designed to withstand high operating temperatures and pressures.
Mold casting requires improved casting properties of the alloy attainable by providing finer-grained structures thereof, which is achieved through selecting an appropriate composition of the alloy.
Additionally, the alloy designed for casting components of thermal equipment must provide a high level of tightness and high-temperature strength, for these components experience high pressures of liquid or gaseous media and high temperatures, on the order of 400.degree. C.
Not a single prior art alloy meets all the above requirements.